Sliding parallel ways for releasing jammed press

ABSTRACT

Method and apparatus for freeing jammed press from dead center position comprising sliding parallel wedge members interposed between dies and die bolster plate adapted to retain fixed position during normal press operation and for relative sliding for relieving pressure upon press jamming.

Unite States Patent William L. Pohjola Southiield, Mich.

Aug. 16, 1968 June 15, 1971 Dover Corporation (De-Sta-Co Division)Inventor App]. No. Filed Patented Assignee SLIDING PARALLEL WAYS FORRELEASING JAMMED PRESS 6 Claims, 5 Drawing Figs.

Int. Cl BZlj 13/02 Field of Search 72/448,

[56] References Cited UNITED STATES PATENTS 2,011,106 8/1935 Lamprecht10/16 2,017,784 10/1935 Clouse 72/448 2,245,573 6/1941 Criley 72/4482,811,057 10/1957 Vosler 72/450 2,826,947 3/1958 Creek 72/448 3,427,8542/1969 Michelson 100/299 Primary Examiner-Charles W. Lanham AssistantExaminer-Gene P. Crosby Altorney Farley, Forster and Farley ABSTRACT:Method and apparatus for freeing jammed press from dead center positioncomprising sliding parallel wedge members interposed between dies anddie bolster plate adapted to retain fixed position during normal pressoperation and for relative sliding for relieving pressure upon pressjamming.

SLIDING PARALLEL WAYS FOR RELEASING JAMMEI) PIRESS BACKGROUND OF THEINVENTION Heavy duty presses which include an eccentric or crankmechanism for opening and closing a die set, to stamp and form metalparts from bar and sheet stock materials, are capable of tremendouspressures in performing such work and consequently are prone to jam orfreeze in an overcenter locked condition, with the dies closed, whenstock materials are over tolerance in thickness, more than one blank isaccidentally placed between the dies, or some foreign member, such as ascrap clip or tool, is unintentionally caught between the dies.

When thi's'occurs, the binding pressures are so great that it isvirtually impossible to force the press through the dead 'centerposition or to back it off, without dismantling the press or burning outone or both of the dies.

Although some presses are made with tie bolts or like means to hold theram and platen parts of a press together, and to facilitate dismantlingwhen necessary, the excessive pressures usually require that a cuttingtorch be used even here, and down time is inevitable for both the teardown and repairs this may necessitate.

SUMMARY OF THE INVENTION The present invention relates to heavy dutypresses for stamping and forming sheet metal and bar stock parts and inparticular to a simple and expedient means of relieving dead centerlocking condition which occur in the accidental jamming thereof.

Parallel sliding ways are used in the practice of this invention and aremounted on the bottom of a die set or on top of a die bolster plate inorder to relieve overload locking pressures, when they occur, to permitthe ram head to be returned. An interlocking keeper is used with thesliding parallels and they are mated and otherwise held and guided sothat upon their release their relative height is reduced and the pressbind is relieved.

No modification of an existing press is necessary to be able to use thepresent invention, other than to accommodate the parallel sliding waysunder the die set or on the bolster plate, and it is a simple matter tofree the sliding ways from each other and to tap one or the other, tocause them to react under the overcenter press load and partsufficiently to enable the press head to be raised, the ways to bereset, and the press operations to be continued as before.

The parallel ways provide an additional known increment of depth orthickness to the die set or bolsterplate and one which is so relativelyminor that it can be readily accommodated in any press. In essence, theways are part of the die set or press, and yet they are not such anintegral part that damage to them, should any occur, is of any seriousconsequence. They may be easily replaced and are of such simpleconstruction as to be of no appreciable expense.

IN THE DRAWINGS FIG. 1 is a front elevation of a press, showing theframe, overhead operating mechanism, bed plate and the use of parallelsliding ways of this invention therewith.

FIG. 2 is a side elevation of the parallel sliding ways, on and ofthemselves, with one of the parts shown in both a full line and a dottedline retracted position.

FIG. 3 is an end view ofthe ways.

FIGS. 4 and 5 are cross-sectional views showing interlocking forms ofthe inclined plane surfaces for the ways which may be used in alternateforms.

DETAILED DESCRIPTION The press shown in the first drawing figureincludes a frame 12 with a bed plate 14 and a slide or ram head 16,guided on the frame side rails 18 and 20, which is reciprocal relativeto the bed plate by a crank throw arrangement operated by a large gear22, shown in dotted outline. The eccentric throw 24 of the crankshaft.26 is shown in its overcenter position and with the connecting rod 28disposing the die bolster plate 30, on the ram head, in spaced relationover the bed plate 14.

Normal practice is to mount the metal forming dies (not shown) on thebed plate 14 and bolster plate 30 as necessary for them to closetogether in serving their intended purpose. When the ram head is drivendown towards the bed plate, the crank throw 24 passes through a bottomdead center position and it is at this moment that maximum metal formingpressure forces are generated. It is also at this time when a press willseize or bind if it cannot pass through the die closing dead centerposition and the problem becomes one of how to relieve the pressureforce for it to pass through or be backed off.

The parallel sliding ways 32 of this invention are shown as disposed onthe bed plate 14 of the press. However, they may be provided on thebolster plate 30 or they may be fastened to one or the other of theforming dies of the set used in the press. 1, t I

In FIG. 2, the parallel ways 32 are shown to include a pair ofcomplementary wedge members 34 and 36 which have their inclined planesurfaces, 38 and Ml respectively, disposed together and, as so disposed,provide top and bottom walls 42 and 44 in relative parallel spacedrelation to each other. The wedge members are truncated, that is, cutoffat their ends, as at 46 and 48, so that they may be relatively separatedwithout end wall interference, and they are fastened together by a crosskey 50 at one end and a screw thread fastener 52 at the other end. 4

The cross key 50 is provided in a transverse slot 54 across the sidewall face of both wedge members and it is fastened to each of them byscrew fasteners 56 and 58. The other fastener 52 is used when this endof the wedge set is accessible so it can be removed. Otherwise, thesliding plane surfaces of the wedges should be formed for interlockingengagement, as shown in FIGS. 4 and 5, or as may otherwise be necessaryto accomplish a like purpose.

In this latter respect, the wedge members 34 and 36 must be joined andheld together to serve as the plane surfaced bearing block capable ofwithstanding all except perhaps the most severe press pressures, whichmight cause damage to dies or other press parts, and in so doing theymust be incapable of shifting laterally as well as lengthwise, untilthey are released. FIGS. 4 and 5 show one means of precluding any sideor lateral shifting between the wedges as assembled and also forassuring guided endwise movement in performing their in tended function.The inclined plane surfaces are simply formed to include interfittingcomplementary shapes providing a center rail key 60, or 62, on one orthe other of the wedge members, 34', 36 or 34", 36" and extending thefull length thereof.

Although only one cross key 50 is shown, more than one and on other thanjust one side of the wedges may be used, if necessary. However, usuallyone will be sufiicient.

In service, the parallel sliding ways 32, as disposed in a press betweenthe die set and the press bed plate 14 or bolster plate 30, will enablea press which becomes locked in dead center condition to be freed bysimply removing the end fastener 52, when provided, and the cross key50, then tapping one or the other of the wedges to cause the bindingpress force itself to cause the wedges to slide relative to one anotherand allow the crank throw to pass through the dead center position andlift the ram head to separate the die set without damage thereto.

Iclaim:

l. The method of relieving binding pressure forces in a metal formingpress, comprising;

mounting parallel sliding ways transversely and relatively between a dieset and a die mounting press part,

keying said ways together for normal press operation use in anonadjustable position to maintain a fixed thickness of the ways.

freeing said ways, relative to each other, for inclined planar slidemovement thereof relieving binding pressure forces in said press, and

returning the ways to the keyed position to restore said fixedthickness.

2. The method ofclaim 1, including keying said ways together on anaccessible sidewall face thereof.

3. In combination with a metal forming press subject to die set lockingpressure forces, the improvement comprising;

parallel sliding ways including complementary wedge members havinginclined planar surfaces received together and providing upper and lowerdisposed walls in parallel relation apart,

means for disposing said ways in a press transversely between a die setand a die set supporting press part,

means for keying said wedge members together for the transmission ofpress forces therethrough and for permitting relative movementtherebetween for the relief of binding press forces as required, and

means to return said ways to a nonadjustable predetermined fixedposition.

4. The improvement of claim 3,

said wedge members having truncated ends permissive of relative slidemovement between the inclined planar surfaces thereof without end wallinterference.

5. The improvement of claim 4,

said keying means including a key slot formed within and transverselyacross the sidewalls of said wedge members near one end thereof, and

a key plate received in said slot and including fastener means ofengagement with the wedge members therebehind and for disengagement ofsaid key plate therefrom.

6. The improvement ofclaim 5,

said wedge members having the inclined planar surfaces thereof formed tocomplement each other and preclude relative lateral movementtherebetween.

1. The method of relieving binding pressure forces in a metal formingpress, comprising; mounting parallel sliding ways transversely andrelatively between a die set and a die mounting press part, keying saidways together for normal press operation use in a nonadjustable positionto maintain a fixed thickness of the ways, freeing said ways, relativeto each other, for inclined planar slide movement thereof relievingbinding pressure forces in said press, and returning the ways to thekeyed position to restore said fixed thickness.
 2. The method of claim1, including keying said ways together on an accessible sidewall facethereof.
 3. In combination with a metal forming press subject to die setlocking pressure forces, the improvement comprising; parallel slidingways including complementary wedge members having inclined planarsurfaces received together and providing upper and lower disposed wallsin parallel relation apart, means for disposing said ways in a presstransversely between a die set and a die set supporting press part,means for keying said wedge members together for the transmission ofpress forces therethrough and for permitting relative movementtherebetween for the relief of binding press forces as required, andmeans to return said ways to a nonadjustable predetermined fixedposition.
 4. The improvement of claim 3, said wedge members havingtruncated ends permissive of relative slide movement between theinclined planar surfaces thereof without end wall interference.
 5. Theimprovement of claim 4, said keying means including a key slot formedwithin and transversely across the sidewalls of said wedge members nearone end thereof, and a key plate received in said slot and includingfastener means of engagement with the wedge members therebehind and fordisengagement of said key plate therefrom.
 6. The improvement of claim5, said wedge members having the inclined planar surfaces thereof formedto complement each other and preclude relative lateral movementtherebetween.